to make a shadow by standing in front of others (see Molina)
Alonso de Molina:
yuuilia. nitlatla. (pret. onitlatlayuuili.) hazer sombra poniendose delante de otros. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 44v. col. 1. Thanks to Joe Campbell for providing the transcription.